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We investigate the effects of a weak gravitational wave, modelled as a gaussian wavepacket, on the polarization state of an
electromagnetic field enclosed in a cavity. Our approach is semiclassical, in that the electromagnetic field is described as a quantum field, while the gravitational perturbation is treated classically,
as a slightly curved background spacetime. Assuming that before the interaction the electromagnetic field has been prepared
in a given polarization state, we show that – due to the gravitational scattering with the wave – some photons having different
polarization states are found in the cavity at late times. Such polarization scattering has some resemblance with Thomson
scattering, well-known in Quantum Electrodynamics: hence the motivation for the title. We give a numerical estimate of the
resulting photon polarization spreading in the case of a typical gravitational burst from a final supernova rebound. We also
briefly comment about the possible influence of such gravitational scattering on the Cosmic Microwave Background (CMB) polarization. 相似文献
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C.R. Mendonça U.M. Neves L. De Boni A.A. Andrade D.S. dos Santos Jr. F.J. Pavinatto S.C. Zilio L. Misoguti O.N. Oliveira Jr. 《Optics Communications》2007,273(2):435-440
In this paper we present optical anisotropy induced by 150-fs laser pulses operating at 775 nm in poly(methyl methacrylate) (PMMA) films doped with Disperse Red 13 (DR13). Two-photon absorption of DR13 induces reversible birefringence in the sample, a feature associated with the molecular orientation caused by isomerization of the azochromophores. No irreversible anisotropy, associated with photobleaching of the chromophore was observed. The slope of 2 obtained for the induced birefringence as a function of the excitation irradiance corroborates the two-photon nature of the process. 相似文献
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Self-injection length in La0.7Ca0.3MnO3-YBa2Cu3O7-δ ferromagnet-superconductor multilayer thin films
We have carried out extensive studies on the self-injection problem in barrierless heterojunctions between La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7-δ (YBCO) thin films. The heterojunctions were formed in situ by sequentially growing LCMO and YBCO films on 〈100〉 LaAlO3 (LAO) substrate using a pulsed laser deposition (PLD) system. YBCO micro-bridges with 64 μm width were patterned both on
the LAO (control) and LCMO side of the substrate. Critical current, I
c, was measured at 77 K on both the control side as well as the LCMO side for different YBCO film thickness. It was observed
that while the control side showed a J
c of ∼ 2 × 106 A/cm2, the LCMO side showed about half the value for the same thickness (1800 ?). The difference in J
c indicates that a certain thickness of YBCO has become ‘effectively’ normal due to self-injection. From the measurement of
J
c at two different thicknesses (1800 ? and 1500 ?) of YBCO films both on the LAO as well as the LCMO side, the value of self-injection
length (at 77 K) was estimated to be ∼ 900 ?. To the authors’ best knowledge, this is the first time that self-injection length
has been quantified. A control experiment carried out with LaNiO3 deposited by PLD on YBCO did not show any evidence of self-injection. 相似文献
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C. C. Santos I. Guedes J. P. Siqueira L. Misoguti S. C. Zilio L. A. Boatner 《Applied physics. B, Lasers and optics》2010,99(3):559-563
In a laser coherent combination, the phase detection and control is the most critical. Using the beat frequency method, consistence
of the phase in output beams can be ensured through real-time detection and correction for the phase change. Phase noises
are controlled by a liquid crystal phase modulator. At the same time, the liquid crystal polarization controller is used to
make the polarization state stable, which is good for the improvement of the combining efficiency. The wave length of the
main oscillation laser is 532 nm. The output power of laser can be adjusted continuously from 0 to 6 W. The shifted frequency
of the system is 40 MHz. The accuracy for phase control is superior to λ/70 RMS. In the process of closed-loop control, using the liquid crystal phase and polarization controller, a better signal
phase correction of optical path has been achieved for the coherent combination of high power laser arrays. 相似文献
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J.C. Pickering V. Zilio 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):181-185
High resolution spectra of neutral silver have been recorded by Fourier Transform Spectrometry in the region 2 000-8 280 ?(50
000-12 000 cm-1) with silver-neon and silver-argon hollow cathode lamps as sources. This work represents order-of-magnitude improvements,
compared to previous work on Ag I, in accuracy of transition wavelengths and wavenumbers, and energy level values. 35 classified
Ag I transitions are given, and the wavenumber uncertainty for the strongest lines is less than 0.002 cm-1. Improved values for 28 energy levels are presented.
Received 31 January 2000 and Received in final form 13 June 2000 相似文献
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V.S. Bagnato L.A.O. Nunes S.C. Zilio H.J. Scheel J.C. Castro 《Solid State Communications》1984,49(1):27-30
Infrared 7FO → 7FJ electronic transitions are reported for Eu+3 in GdAlO3. The low symmetry of the crystalline field allows the observation, for the first time, of transitions with J = 3, 4, 5 and 6. The spectra are explained by means of a crystal-field model where a Cs term is added as a perturbation to the cubic field in order to take into account the lattice distortion. This model predicts energy levels which are in good agreement with the experimental data. 相似文献
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